1. Technical Field
The present invention relates to computer data storage systems. In particular, it relates to the organization and partitioning of data in Fiber Channel (FC) based storage area networks (SANs) into storage domains (SDs) that are controlled by Storage Domain Servers (SDSs) such that global control and access to data storage is provided by the SDS.
2. Background Art
The development of computers initially focused on local systems with attached dedicated storage devices. Over time, communication systems were developed to allow sharing of data between computers. However, these early systems were slow and often not capable of allowing widespread or complete access to data across the network. As the need for data sharing between systems increased, a more effective method of controlling access to data between systems was needed.
Today, computing systems face a crisis in data access, storage, protection and availability. Critical data is now found on all platforms spread throughout the enterprise. This information is often isolated, incompatible, and too slow to respond to the emerging needs of the enterprise. However, while the storage and retrieval of common data by the entire enterprise is now a requirement, much of that data currently resides on incompatible, disparate, and isolated storage systems organized as localized “islands of information.” As a result, while the need to access data is global throughout the enterprise, control of that data is local. It would be desirable to have a system that could provide global control of data throughout the enterprise.
Isolated islands of storage were acceptable as long as enterprise applications were also isolated to a given locality or operating system cluster and amongst a small number of server platforms. With the advent of large-scale networking, enterprise applications have proliferated onto a myriad of interconnected computer systems. The combination of networked servers and private storage has guaranteed that data is allocated, replicated, and managed in an ad-hoc manner. Today the limitations of storage technology determine the manner in which data is organized and presented. It would be desirable to be able to manage data on a large-scale, across interconnected computer systems, in such a manner that data availability could be controlled in a uniform and comprehensive manner and not limited by the particular storage technology being used.
Until recently, data storage devices have required close coupling to computing systems. High bandwidth access was achieved through distance limited connections in point-to-point configurations. Early mass storage control techniques recognized these physical limitations and concentrated storage in large locally attached storage controllers. These controllers provided high levels of connectivity combined with large storage capacity. To achieve high levels of performance these early controllers were also proprietary, expensive, and complex in design.
The networking of these storage controllers was impractical due to the limitations in bandwidth of early network technologies. These technologies could not eliminate the problem of “islands of information.” In part, this was due to the fact that the logical allocation of storage resources between these controllers was impossible.
One step in the solution to the problem of providing adequate access to data has been the development of high-speed Fiber Channel (hereinafter “FC”) connections. It should be noted that, for the purpose of this discussion, the term “fiber” in fiber channel can be used to denote either an optical or an electrical (i.e. copper wire) connection. FC connections provide computer systems with extremely high-speed data transfer rates. For example, they can deliver sustained bandwidth's of over 97 MB per second. In addition, due to their relatively low cost of implementation, cost per megabyte of data transfer is low.
Another advantage of FC technology is that, unlike other data transfer mechanisms such as ethernet, FC technology is protocol independent. It can be used for transferring audio/video, TCP/IP, Internet Protocol (IP), SCSI data, etc. FC technology also provides advantages over prior technologies due to the large distances which can be supported without serious degradation of performance or reliability. For example, FC systems can support devices as far away as ten kilometers. As a result, as computing networks control and support ever larger data volumes, data transfer rates, and total numbers of users, FC architecture has emerged as important element in the solution to the problems related to managing data in those large-scale networks.
Another element of the solution to storage management problems has been the development of storage area network (“SAN”) products. A SAN is a connection scheme between computers and storage peripherals which is based on an FC data transport mechanism. SANs typically use FC technology as the data transport means between multiple systems and networks due to their excellent performance and reliability.
A Storage Area Network (“SAN”) can be defined as an architecture composed of a group of storage systems and servers that are connected together via Fiber Channel (FC) equipment, such as a switch or hub. The introduction of SANs provides some partial solutions to a number of problems related to the “islands of information” in global storage systems. These solutions are limited to high bandwidth, increased connectivity, and robust topologies using FC hubs and switches. However, SANs address only two of the emerging enterprise storage requirements: improved connectivity and higher bandwidth. The resultant storage systems themselves remain proprietary and non-interoperable. The other requirements, such as interoperability, storage resource allocation and management, and high performance, have not been addressed with today's SAN architectures.
Despite their promise, SANs today are largely confined to two areas: 1) as extended server host and device connection methods for proprietary storage controllers; (i.e. as the backbones for vendor “private” networks); and 2) as storage networks specific to applications, typically those in which direct access to physical disks (1 to 1 mapping) is required and storage administration is limited or nonexistent. Other critical requirements, such as storage resource allocation and management, security, administration, and interoperability have not been addressed with today's SAN architectures.
SANs therefore have two major limitations. First while they may provide extended host and device interconnection for proprietary storage controllers on private networks, the resulting storage systems are isolated and not interoperable within the enterprise as a whole. Second, storage networks are tied to specific applications and provide only one-to-one mapping. For example, in Windows/NT™ systems, NT will seek out and attempt to control all drives within the network even if those drives are required to be logically separated. Within UNIX, each OS will attempt to logically map all attached devices. Therefore, in UNIX, there is no centralized management and security structure which is aware of the overall storage management structure of a distributed system. SANs therefore increase the exposure of data storage systems to corruption because they lack a network oriented logical to physical mapping facility for disk drives, controllers, and operating systems. SANs allow a large number of devices to be attached to a system; however the visibility of these devices to the system is insufficient to “virtualize” the physical devices into logical pools of integrated and secure storage. It would be desirable to improve upon SANs with a system that bridges the logical mapping requirements of operating system file services, physical devices, and the SAN interconnection to provide universal data resource control and availability in conjunction with the performance and conductivity advantages of SANs.
While addressing the basic desirability of using SANs to provide wide scale access to data, the prior art has failed to provide a uniform and secure method of using SANs which also provides universal access and logical mapping of data across large-scale computing environments independent of the storage platforms used in the system.